A lot of software connects to internet servers in order to work. It means that some of the work of this software is done on the server. And not on the user's computer. Meaning, the user looses some control over the computation. The server could be Free Software as well. Meaning, if users don't like something about the server, they can start another one, fixing all their problems. And connect to it instead. But other servers might be proprietary or secret. In this case, you are on the mercy of the server maintainers.
